Figure 1
Individual episodic prolactin patterns during the whole bleeding period (B) and expanded detail of the pulsatile pattern of prolactin during the last 2 hr and 25 min of bleeding (A). The arrows indicate the prolactin pulses during the studied period. The left upper panel (I) shows the pulsatile pattern of prolactin in control rats treated with saline (vehicle of L-NAME). The left lower panel (II) shows the pulsatile pattern of prolactin in rats treated with L-NAME (rats were ip administered Nω-nitro-L-arginine methyl ester at a dose of 10 mg/kg in saline, 60 minutes before the beginning of the bleeding period). The right upper panel (III) shows the pulsatile pattern of prolactin in rats treated with MTX (animals were sc treated with MTX al a dose of 25 mg/kg/day for 1 month). The right lower panel (IV) shows the pulsatile pattern of prolactin in rats treated with MTX and L-NAME (the animals were sc treated with methoxychlor (25 mg/kg/day) for 1 month and L-NAME at a dose of 10 mg/kg in saline, 60 minutes before beginning of the bleeding period).
Table 1
Mean serum prolactin levels, absolute and relative pulse amplitude, frequency and duration of the pulses, and mean half-life of prolactin, in adult male rats.
| Group | rPRL-RP3 (ng/mL) | Absolute Amplitude (ng/mL) | Relative amplitude (%) | Frequency (Pulses/3 h) | Duration (min) | Half-life (min) |
| Control | 0.56 ± 0.11 | 0.43 ± 0.05 | 1.92 ± 0.23 | 5.17 ± 0.4 | 29.87 ± 3.92 | 20.19 ± 2.37 |
| L-NAME | 0.97 ± 0.10** | 0.59 ± 0.03* | 1.29 ± 0.39 | 4.90 ± 0.2 | 30.03 ± 2.39 | 19.06 ± 1.44 |
| MTX | 1.26 ± 0.26* | 0.73 ± 0.08** | 0.85 ± 0.17** | 5.50 ± 0.5 | 27.01 ± 1.56 | 16.18 ± 0.81 |
| MTX + L-NAME | 1.02 ± 0.27 | 0.32 ± 0.11#,& | 0.77 ± 0.21** | 5.25 ± 0.4 | 29.50 ± 2.10 | 25.30 ± 3.74# |
The relative pulse amplitude was calculated as the quotient between absolute pulse amplitude and preceding nadir value. Values are expressed as mean ± S.E.M. The number of animals per group is 8. *P ≤ 0.05 ≤; **P ≤ 0.01 vs. Control; #P ≤ 0.05 vs. MTX group; &P ≤ 0.05 vs. NAME group.
Control group: the animals were ip injected with saline 60 minutes before beginning of the bleeding period, and vehicle 0.5 mL of sesame oil (vehicle in which MTX was administered in MTX group) for 1 month.
L-NAME group: the animals were i.p. administered Nw-nitro-L-arginine methyl ester (L-NAME) at a dose of 10 mg/kg in saline, 60 minutes before beginning of the bleeding period.
MTX group: the animals were sc treated with methoxychlor (25 mg/kg/day) for 1 month.
MTX + L-NAME group: the animals were s.c. treated with methoxychlor (25 mg/kg/day) for 1 month and L-NAME at a dose of 10 mg/kg in saline, 60 minutes before beginning of the bleeding period.
Figure 2
Dopamine (DA) content in the median eminence (ME), and in the anterior (AH), mediobasal (MBH) and posterior hypothalamus (PH) in the adult control group, MTX-treated rats, L-NAME-treated animals and MTX plus L-NAME-treated rats. The values are expressed as mean ± S.E.M. (n = 8 in each group). *P ≤ 0.05; **P ≤ 0.01 and ***P ≤ 0.001 vs. control group; #P ≤ 0.05 and ##P ≤ 0.01 vs. MTX group; &&P ≤ 0.01 and &&&P ≤ 0.001 vs. L-NAME group.